publications > circular > Circular 1134 > water and environmental stress > degradation of water quality > big cypress swamp U.S. Department of the Interior U.S. Geological Survey Circular 1134 Water and Environmental Stress Degradation of Water Quality Big Cypress Swamp The quality of water in the remote, undrained parts of the Big Cypress Swamp is good and probably best reflects south Florida's pristine water-quality conditions. The Everglades, on the other hand, has been affected more than the Big Cypress Swamp by land-use and water-management practices, and water quality, particularly in the northern part of the Everglades, is of poorer quality than that in the swamp. Most of the water-quality data described below were collected more than 20 years ago. The concentrations of dissolved solids indicate general water-quality conditions of a freshwater environment. In samples collected in the Big Cypress Swamp in the 1960's, concentrations averaged about 250 mg/L (Klein and others, 1970). In the northern Everglades, for comparison, concentrations at three long-term stations (1950-70) averaged 471 to 541 mg/L (McPherson, 1973). Sources of dissolved solids include limestone, agricultural and urban runoff, salty artesian ground water, and seawater. In the northern Everglades, dissolved solids are attributable primarily to saline ground water and agricultural runoff, whereas in the Big Cypress they are attributable to exposed, soft limestone. Interestingly, dissolved-solids concentrations from samples collected at a long-term station (1950-65, 1969) in the southern Everglades averaged 205 mg/L (McPherson, 1973). The relatively low value probably reflects an environment with little exposed limestone. Concentrations of nitrogen and phosphorus in the surface waters of the Big Cypress also are usually low compared with concentrations in water in the urban and agricultural canals of south Florida (Klein and others, 1970). Although water quality in the Big Cypress Swamp is good, it has been degraded to some extent by human activities. Canals in the western part of the swamp transport potentially toxic metals to the estuaries in concentrations and amounts that are greater than those transported by overland flow (Little and others, 1970). Magnesium, iron, cobalt, cadmium, copper, zinc, and lead have been concentrated above natural levels in Chokoloskee Bay presumably because of transport down the Barron River and the Turner River Canals from agricultural land to the north (Horvath, 1973; Mattraw, 1973). Concentration of pesticides are low in surface water of the Big Cypress Swamp, but are concentrated in soils and biota (Klein and others, 1970). Although chloride concentrations tend to be low (averaging about 20 mg/L) in the interior parts of the Big Cypress, high concentrations (as much as 5,350 mg/L) have been detected around several exploration oil-well sites (Wimberly, 1974). Nutrients transported from drained parts of the Big Cypress Swamp to the estuaries exceed those transported by overland sheetflow in the undrained areas. The Faka Union Canal (fig. 23) transports to the estuaries almost 5 times as much Kjeldahl nitrogen (ammonia and organic nitrogen), 10 times as much total phosphorus, and 7 times as much organic carbon as the Fakahatchee Strand transports by sheetflow (Carter and others, 1973). Trace elements concentrated in fine-grained organic sediments (less than 20 microns), also are transported to the estuaries by canals that extend to agricultural land in the north (Mattraw, 1973). Fine-grained sediments are readily transported when canal flow is high and are deposited with mangrove detritus in the estuaries. Because mangrove detritus is a major food source, its enrichment may provide a pathway for the metals to enter into the estuarine and marine food chains (Mathis, 1973). Metals transported from the drained parts of the Big Cypress Swamp to the estuaries also exceeded those transported by overland sheetflow in the undrained areas. Chokoloskee Bay, which receives heavy metals from the Barron River Canal, has greater loads of these metals in its waters and sediments than more remote bays and estuaries to the south that do not receive canal flows (Horvath, 1973; Mattraw, 1973). Next: Degradation of water quality in the Charlotte Harbor Watershed Go to top Return to Publications Page

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Last updated: 02 November, 2004 @ 07:32 AM(KP)